Means for controlling the fluid level in a drill string



July 22, 1941. R. E. TINSLEY MEANS FOR CONTROLLING THE FLUID LEVEL IN A DRILL STRING Filed April 1, 1939 Patented-July 1941 f UNITED, STATES PATENT OFFICE MEANS For. CONTROLLING 'rna rwm mvsnmanmsmmd mm s; 'linsley. man, can. Application April 1,1939, Serial No. 265,408

(01. ass-1 vI Claims.

' This invention relates to means for controlling the mud, or other fluid, level inside a well and drill string after circulation has been stopped and the drill string is being removed from or inserted in the well.

During a rotary drilling operation the mud or other drilling fluid that is being circulated down the drill string, becomes loaded with detritus and cuttings from the bit,- and consequently the mud on the outside oi! the drillstring is much heavier than the mud on the inside, and this causes the mud on the inside of the drilltubin the tool string may'extend almost the height of a stand of pipe above the point'at which the stand is disconnected or broken out," which'is usually slightly above the derrick floor. Conse-' quently, wheh the 'drill pipe is disconnected at .the floor of the derrick, this mud will spill out as the Joint is disconnected, and flow out over the top of the drill pipe still remainingin the well. This. mud covers the derrick floor and is of course very disagreeable for the rough-necks working on the well. The slippery mud also greatly increases "the chance of accidents occurring. But important also, is the loss ofthe mud.-

In other cases where the level of the mud in the drill string is not above'the level 01 the derrick'iioor, nevertheless in the usual pulling of a drill string, considerable mud adheres to the inside of each stand of pipe as it is pulled,,'and

the loss oi this adhering mud will lower the mud level and'reduce the hydrostatic pressure of the mud to such an extent that blow-outs of mud may occur. It also would reducethe mud pressure on the sides of the well hole, which hm d be avoided.

It is desirable that the well be kept full of fluid while the drill string is being pulled, in order to prevent caving oi the walls which might occur if the fluid level were allowed to drop, which it normally would do. The wellcrew, on the other hand, prefer to let the fluid lev'el 'drop far enough so that when the drill string is pulled, the sections,'as they are disconnected, will be dry.

One of the objects 01' this invention is to provide a simple method and means for overcoming thesedifliculties. i

A further object of the invention is to provide a simple method and means for preventing the a pulling operation to be accomplished with a minimum quantity ogmud, but at the same time maintaining the normal mud pressure on the well.

A further object of the invention is to provide a simple method and meansior wiping the mud internally from each stand of pipe as the same is toriseto a considerablvhigher level than the mud on the outside, and sometimes the mud in pulled up into the derrick.

In practicing the invention, I provide a loose piston that I insert in the tool string. This piston loads the mud within the drill string and depresses the level of the mud therein below' the derrick floor.. In a pulling job, if the tubing has become broken, it is evident that when the break in the tubing reaches this piston, the

piston would get out of the tubing and become lost in the well, necessitating a real fishing job to recover the same; One of the objects of this invention is to provide simple means for preventing the loss of the loose piston, and to enable it to be automatically caught and pulled up'with the lower broken end of the tubing.

Further objects of the invention will appear I hereinafter.

The invention consists in the novel method and means, the features of which contribute to produce an efllcient method and means for controlling the mud in tubing as the same is pulled, all

' a drill string in the vicinity of the piston, and

showing a portion of this device in section. This view illustrates means for automatically catching the device to enable it tobe withdrawn with the broken end of the tubing. 'I'hisviw shows the device in its set position as it would have before being reached by a break in the tubing.

Fig. 4 isa view similar to Fig; 3, but illustrating the automatic catching device in its operating position after the break in the tubing has reached mud level in the drill string from rising above the derrick floor, and to conserve the mud and prevent loss of the same in pulling operations.

A iurther object of the invention is to enable the location oi the piston.

In practicing the invention, I provide a loose plug or piston I that I insert into the bore of the tubing}. This piston yielding fills the bore 01' the tubing and paw s the same 0 as to hold the mud below it. In 0th r words, it is supported on, but not floating on, the driding fluid or mud. j

a mud back of! the wall.

I preventing loss of mud, and

' curs, of course, the plug I will 2 Hence the weight of the piston loads the mud in the tubing.

The piston I, which or swab, consists of a end of which isthreaded to give the necessary weight to it. I

The body] is provided with a-wiper sleeve 9 may also be called-a wiper, tubular body I, the lower preferably in the form of a soft sleeve resembling a swab but preferably provided with a tapered lip i at 'its J of this sleeve is pro ided with a metalferrule or binder Ii that seats against the lower end of the sub 8. This binder prevents any-possibility of the soft sleeve 9 being dislocated when dropped into the tubing 2.

When the tubing is pulled with this piston and wiper device in the tub the weight of. the wiper depresses the mud le e1 inside the tubin so that by the time the sta d of tubing is broken out, the mud level is at or which the drill string stands are disconnected. Inthe present instancethiswouldbe at the derrick floor. The piston maintains the mud pressure in the well; and when a stand of the tubing is the upper end of which is secured at is to the j into a weight section! 5 lower end. The upper end below the point at pulled up into the derrick to be broken out, the lip l0 and the sleeve "body 4 wipe the adhering I-Ience there is very little mud if any in the stand when broken out, thereby enabling the pulling job to be a comparatively clean one.

slowly so as to keep the hole full of fluid while the tubing is being'withdrawn from the well.

In order to enable the wiper to be retrievedwithin it while running the drill string down into This can be accomplished while themud pumps are running when desired, its upper end may be provided with an undercut head ii that can be caught by an overshot fishing tool on a line from the mouth of the well.

As a safety feature'to enable circuiation to be valve i4 is provided at the lower end of the body 4, that permits such. circulation. When this ocsink to the bottom of the tool string, but this cannot shut off circulation of mud tothe drill because I provide the lower end of the bottom section 5 with a trans verse recess 5'. This prevents the lower end from'plugging the mud outlet at the drill bit.

The weight section of the device etal is a m interior of the body and conduct downcoming mud out into.the tubing. Inlet ports I in a sub 8 carried in the upper end of the body 4, cooperate with the port 1 to enable mud to'be\ circulated down from above if mud circulation has to be resumed. I

The weight nebessary forthedevice can"be reduced byplacin'g the packing sleeve 9 at the lower end instead of at the upper end. In that resumed if necessary,adownwardly opening check 40 side of the part 5, and extends a considerable distance below the socket II; at the socket it is provided with a nib or shoulder 20 that engages the upper end of the slip. This spring l8 tends by its resiliency to force its lower end outwardly against the side of the tubing 2. A pair of small leaf springs 2| attached to the slip,

.rub on the inner face of the tubing. In pulling the tubing, if a break 22 has occurred in the tubing, whenv this break passes above the lower end of the spring i8, the spring forces itself outwardly, and in this way releases the upper end of the slip l5 from the shoulder or nib 20. Due to the release of the mud at the-broken point 21, the piston will be unsupported and will start to fall. As it does so, the slip I! will Jam on the inclined face it and lock the-piston into the lower end of the tubing (-see Fig. 4). Hence if the broken end of the tubing is pulled up, the i will be recovered with it.

It is obvious that this piston I may be employed in a drill string for keeping down the fluid level piston X piston filling the bore of the tool string a freely movable within the same and resting on the mud, said piston operating by its own weight to depress the mud level within the tool string, and also operating to wipe the mud from the interior of the tubing when the same is being pulled; andautomatic means'for catching the piston in the tool string brought into action 'by a break in the tool string when the break arrives I at the piston.

lar toolstring carrying mud with a weighted piston filling the bore of the tool string freel movable within the same andresting on the mu body with ports Bthat communicate with the 5 case the mass of the metal would not be immersed in the mud and would consequently'have more dead weight. Of course; the solid section:

i can have any length necessary to give the pis-,

ton l the requisite weight.

The, weight of the piston l depresses the mud level considerably. No mud can be thrown out at the wells mouth, as" the piston will not rise sumciently to permit In Figs. 3 and '4 I illustrate an automatic catching. device to prevent the piston i from 7 becoming ,lost in. the/well if a break hasoccurred in the drill string that is being. pulled. For this purpose Iprovide the weight section 5" of the device with a tapered slip I! that is received in a socket i6 cut in its side face and said piston operating by'its own weight to depress.t he mud levelwithin the tool string, and also operating to wipe the mud from the interior of the tubing when the same is being pulled; said piston having .a slip mounted in the side thereof with means carried on the slip for frictionally engaging the wall of the tool string, and a resil-.

ient member carried by the piston extending down below the same and having means for normally engaging the slip to ,prevent the same from operating, said resilient means operating when abreak arrivesat the piston, to swing outwardly at its lower endand thereby release the slip,- said slip cooperating with the piston thereafter to catch the piston in the tool string.

3. In a drilled well, thecombination of atubular tool-string carrying mud, with a packed piston constructed so movable in the tool-string, filling the bore of the tool-string, and resting; and supported upon,

the mud, -so as to depress the mud level.

4-. In a drilled well, with a hoist for pulling," and -"breaking out" tubing, the combination of a tubular tool-string carrying mud, a l'oosefreely -movable piston having a packing sleeve carried'i in the bore of the tool-string and resting on the mud, and normally depressing the mud level bethat it lies within and is freely I to prevent mud from being carried up and spilled at the wells mouth.

5. In a drilled well, with a hoist for pulling and breaking out" tubing, the combination of a tubular tool-string carrying mud, a loose freely movable piston having a packing sleeve carried in the bore of the to ol-string and resting on the mud, and normally depressing the mud level below the point at which the drill string is disconnected when pulling the same. said piston opprevent mud from being carried up to the wells mouth and spilled at the wells mouth, said piston having a duct leading to the same above the packing sleeve, and a d wnwardly opening check valve in said duct for conducting downwardly circulating mud past the packing sleeve.

6. In adrilled well, with a hoist for pulling andfbreaking out" tubing, the combination of a tubular tool-string carrying mud, a loose freely movable piston having a packing sleeve carried in the bore of the tool-string and resting on the mud, and normally depressing the mud level below the point at which the drill string is discrating as a wiper when the'tubing is pulled to connected when pulling the same. piston operating as a wiper when the tubing is pulled to prevent mud from being carried up and spilled at the well's mouth, said piston having a duct leading into the same above the packingsleeve, and a downwardly opening check valve in said duct for conducting downwardly circulating mud pastthe packing sleeve, the bottom end of said piston having a transverse recess operating to prevent the lower end of the piston from plugging the mud outlet at the drill bit if the piston should descend to the lower end'of the drill string. l a

7; A device for removing drilling fluid from a string of drill pipe being pulled upwardly through a-derrick floor comprising a body member slightly smaller in diameter than the inside diameter of said pipe, resilient means surrounding said body member and adapted to contact the inner surface of said pipe so aslto flllthe annular space between said body member and the inner surface of said pipe, said device having sufliclent weightto force drilling fluid down- .wardly through said pipe string and to maintain the level of the fluid below said derrick floor while the pipe string is being raised. 7 ROBERT E. TINSLEY. 

